1. Technical Field
The present disclosure relates to an electronic device and a method for manufacturing the electronic device. The present disclosure relates more particularly to an electronic device with a pressure-contact electric connection terminal structure and a method for manufacturing the electronic device.
2. Description of the Related Art
A power converter including a power semiconductor device is mounted on a household appliance, a power conditioner, industrial equipment, an electric vehicle, a railroad vehicle, or the like. This power converter is composed of a converter circuit, an inverter circuit, or the like. Since the power converter handles a large current of several A or more and high power, a power semiconductor device is used as a circuit component. Power semiconductor devices include a component (which is generally several centimeters square and several millimeters thick), such as a transistor or a diode in bare chip form made of, for example, Si, SiC, or GaN. Examples of a packaged form of such a component include a discrete component and a power module.
A description will be given of the configuration of a power converter including a power semiconductor device, particularly the general structure of a power module.
A general power module includes a board, and a power semiconductor device is electrically connected to the board by bonding the power semiconductor device to wiring of or a support for the board through die bonding. For the connection, solder joining is generally used. A conductor, such as wiring of the board, a lead frame, or a terminal, is electrically connected to an electrode on a surface on the other side of the power semiconductor device by a conductive wire. Wire bonding is mainly used for the connection. A structure formed through the above-described connection is housed in an insulative case except for an external terminal.
During operation, a current of several A to several thousands of A or more flows through the power semiconductor device to generate heat. The heat generation raises not only the temperature of the power semiconductor device but also the temperature of a device including the power semiconductor device to a high temperature of, for example, several tens of ° C. to 100° C. or more. A metal conductor included in the device including the power semiconductor device increases in electric resistance and becomes more likely to generate heat with increase in temperature. If the device has low heat dissipation, and the temperature inside the device remains high and is slow to drop, the electric resistances of the power semiconductor device and the conductor increase to generate more heat. This leads to the vicious cycle of the temperature inside the device rising increasingly. In some cases, the power semiconductor device may be thermally destructed or resin may degrade due to thermal fatigue or may be brought to stress rupture due to thermal expansion. For this reason, the device including the power semiconductor device needs high heat resistance and a high heat dissipation technique.
The melting temperature of solder used for connection of the electrode on one surface of the power semiconductor device is about 130° C. to 300° C. The temperature of a joint of the power semiconductor device is 100° C. or more during operation, and solder may melt to cause poor reliability. A bonding wire used to connect the electrode on the other surface of the power semiconductor device is also used as a path for heat dissipation from the power semiconductor device. Since the bonding wire is in contact with only a part of the surface of the power semiconductor device and has a small diameter, the bonding wire has low heat dissipation.
From the foregoing, it can be seen that high heat resistance and a high heat dissipation connection technique are important in an electronic device including a semiconductor, such as a power semiconductor device, or a component, such as a passive component. Under the circumstances, a pin connection technique is being developed as a connection structure in a power semiconductor device (see, for example, Japanese Unexamined Patent Application Publications Nos. 2009-267246, 2012-151019, and 2013-125804).
In the electronic device in any of Japanese Unexamined Patent Application Publications Nos. 2009-267246, 2012-151019, and 2013-125804, members in the device are connected using an elongated pin, and heat is dissipated through transfer of heat via the pin.